chore(ci): update CI to lastest node versions & github actions

* update CI node versions to match node supported versions
* remove node 17.x on appveyor, it only supports up to node 16.x
* travis CI is not longer free/working; remove it in favor of github actions

.appveyor.yml

@@ -7,15 +7,17 @@
 # What combinations to test
 environment:
   matrix:
-    - nodejs_version: "6"
+    - nodejs_version: "12"
       platform: x64
-    - nodejs_version: "6"
+    - nodejs_version: "12"
       platform: x86
-    - nodejs_version: "8"
+    - nodejs_version: "14"
       platform: x86
-    - nodejs_version: "8"
+    - nodejs_version: "14"
       platform: x64
-    - nodejs_version: "10"
+    - nodejs_version: "16"
+      platform: x86
+    - nodejs_version: "16"
       platform: x64
 cache:
   - node_modules

.github/workflows/node.js.yml

@@ -0,0 +1,30 @@
+# This workflow will do a clean install of node dependencies, cache/restore them, build the source code and run tests across different versions of node
+# For more information see: https://help.github.com/actions/language-and-framework-guides/using-nodejs-with-github-actions
+
+name: Node.js CI
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        node-version: [12.x, 14.x, 16.x, 17.x]
+        # See supported Node.js release schedule at https://nodejs.org/en/about/releases/
+
+    steps:
+    - uses: actions/checkout@v2
+    - name: Use Node.js ${{ matrix.node-version }}
+      uses: actions/setup-node@v2
+      with:
+        node-version: ${{ matrix.node-version }}
+        cache: 'npm'
+    - run: npm ci
+    - run: npm test

.travis.yml

@@ -1,26 +0,0 @@
-language: node_js
-node_js:
-  - "6"
-  - "8"
-  - "10"
-
-before_install:
-  - npm install -g grunt-cli
-
-# travis build  speed up
-sudo: false
-cache:
-  directories:
-    - node_modules
-
-# scripts
-script: grunt test
-
-# hooks
-notifications:
-  webhooks:
-    urls:
-      - https://webhooks.gitter.im/e/e369617839852624aa69
-    on_success: change  # options: [always|never|change] default: always
-    on_failure: always  # options: [always|never|change] default: always
-    on_start: false     # default: false

README.md

@@ -1,6 +1,6 @@
 ![Showdown][sd-logo]
 
-[![Build Status: Linux](https://travis-ci.org/showdownjs/showdown.svg?branch=master)](https://travis-ci.org/showdownjs/showdown)
+![Build Status: Linux](https://github.com/showdownjs/showdown/actions/workflows/node.js.yml/badge.svg)
 [![Build Status: Windows](https://ci.appveyor.com/api/projects/status/github/showdownjs/showdown?branch=master&svg=true)](https://ci.appveyor.com/project/tivie/showdown/branch/master)
 [![npm version](https://badge.fury.io/js/showdown.svg)](http://badge.fury.io/js/showdown)
 [![Bower version](https://badge.fury.io/bo/showdown.svg)](http://badge.fury.io/bo/showdown)